Present damage-risk criteria (DRC) for daily 8-hr exposure to intermittent noise are based on extrapolation from meager data. It is certain that the equal-energy hypothesis traditionally used (a hypothesis that assumes that the temporal pattern is irrevelant and that only the total energy matters) leads to DRC that are too conservative, since no account is taken of the recuperative powers of the ear between noise bursts. On the other hand, a recent American DRC sponsored by the Committee on Hearing, Bioacoustics and Biomechanics (CHABA) of the National Research Council may not be conservative enough, according to empirical evidence that has since accumulated. Therefore it is proposed to determine DRC for intermittent noise directly, based on the assumption that any pattern of noise exposure over an 8-hour period is safe if the auditory fatigue (temporary threshold shift, or TTS) thereby produced has disappeared after 16 hours of rest. Normal-hearing young adults will be exposed for 6 or 8 hours to noise patterns with duty cycles ranging up to 50 minutes, with on-fractions of 1/2, 1/4,l/8, etc. The intensity level for each such pattern will be gradually increased in successive sessions until the particular TTS is produced that just barely recovers in 16 hours. DRC based on the results will then be constructed. BIBLIOGRAPHIC REFERENCES: William A. Ahaus and W. Dixon Ward, "Temporary Threshold Shift from Short-Duration TTS; Implications for Noise Exposure Standards," J. Am. Audiol. Soc. 1, 4-10 (1975). W. Dixon Ward, E. Marion Cushing, and Edward M. Burns, "Effective Quiet and Moderate TTS; Implication for Noise Exposure Standards," J. Acoust. Soc. Am. 59, (January 1976).